A SiC/Mo(Six, Al1-x)2 oxidation-resistant coating for carbon/carbon composites
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摘要:
为了提高炭/炭(C/C)复合材料的高温抗氧化性能，应用多相反应技术在C/C复合材料表面制备SiC/Mo(Six、Al1-x)2复合涂层。利用扫描电镜、电子能谱、X射线衍射仪等测试手段对涂层材料的微观结构和物相组成进行分析，同时研究涂层C/C复合材料在超音速气流中的抗氧化性能。结果表明,C/C复合材料表面形成的抗氧化涂层显示出明显的双层结构，从外向内分别为Mo(Six、Al1-x)2与SiC的复合层和纯SiC层，同时有少量的Mo4.8Si3C0.6存在于涂层中。在温度为1800K、气体速率1500m/s的超音速气流中氧化冲刷96s，以及在2550K和室温下热循环24次的测试条件下，制备的SiC/Mo(Six、Al1-x)2涂层材料均未发生破坏现象。涂层材料优良的抗氧化性能和抗热震性能主要归因于基体C/C复合材料的高强度以及在氧化过程中材料表面形成的连续稳定的SiO2和Al2O3玻璃相。
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关键词:
- SiC/Mo(Six、Al1-x)2涂层 /
- 炭/炭复合材料 /
- 多相反应技术 /
- 氧化行为 /
- 抗热震性能
Abstract:SiC/Mo(Six, Al1-x)2 multilayer coatings were prepared on carbon/carbon (C/C) composites using a multi-phase reaction technique to improve their high temperature oxidation resistance. The microstructure and phase compositions of the multilayer coatings were investigated by SEM, XRD and EDS. The coating exhibits a binary-layer microstructure, i.e. an outer Mo(Six, Al1-x)2 layer and an inner SiC layer with a small amount of Mo4.8Si3C0.6. The oxidation behavior of the coated C/C composites was evaluated in a supersonic flow of about 1500m·s-1 at 1800K in a wind tunnel. No destruction of the coated C/C composites was found after 4s oxidation after 24 exposures and thermal cycling between room temperature and 2550K for 24 times in air. The excellent oxidation resistance and thermal shock resistance are attributed to a high cohesion between the layers and the C/C composite, and the formation of a continuous and stable glassy film consisting of SiO2 and Al2O3 on the coated layers during oxidation.
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